Not applicable.
Not applicable.
1. Field of the Invention
This invention relates in general to a cage for a roller bearing, more particularly, to a unitized cage for a cylindrical roller bearing.
2. Description of Related Art
In applications where the bearing shaft and housing can be hardened and ground to roller bearing specifications, the use of cylindrical rollers without the inner and outer ring can reduce the section height and weight requirements of the power transmission component. In such applications, there is no need for the inner and outer rings because the bearing raceways which would normally be found in the inner and outer rings is now found on the surfaces of the shaft or the housing for the bearing.
One typical application that utilizes this arrangement are heavy industrial planetary gearboxes, where the planet pin and gear bore are hardened and ground to act as the bearing raceways. In this configuration, the cylindrical rollers can be used with or without a cage. When used without a cage, the speeds are usually lower, to prevent scuffing damage between the cylindrical roller bodies. Also, roller skewing is not as tightly controlled, which can cause problems at higher speeds. The unitizing cage of the present invention spaces the cylindrical rollers to prevent scuffing of the roller bodies and prevents skewing, all of which, if not prevented, can lead to reduced bearing performance. Finally, when the cylindrical rollers are not unitized with a cage, the assembly of the final gearbox is considerably more time consuming and costly than when a cage unitizes the cylindrical rollers.
To unitize the cylindrical roller cage assembly, several configurations have been used. Most commonly, machined steel separators are placed between the rollers, and then fixed to two end rings with rivets or pins, thus holding the assembly together. Because the separators are machined from a solid piece of metal, they are expensive to manufacture. Also, they require several steps to assemble due to the forming of a head on the rivets or welding of pins. U.S. Pat. Nos. 3,647,273 and 4,435,024 are representative of these types of cages.
While this invention may be similar in some aspects to the U.S. Pat. No. 4,435,024, the present invention is designed to be used without bearing rings. Without bearing rings, the cage design must be stronger to prevent roller skewing, to allow for roller separation during extreme operating conditions, and to allow roller retention during initial assembly and assembly/disassembly for routine maintenance.
In U.S. Pat. No. 4,435,024 the cage was designed to simplify the manufacturing and assembly of a standard stamped steel cage used in a bearing with an inner and outer ring. One of the bearing rings in that patent contains two ribs to axially locate the rollers and prevent roller skewing. However, unlike the present invention, the previous patent would not be sufficiently strong for unitizing the rollers without bearing rings.
Other past configurations use two pins without the machined separator, however, this is still expensive to manufacture with the welding operation of the pins. Still other past configurations require intricate forming of sheet metal which might not have the strength to maintain their shape during severe operation, and are expensive to manufacture due to the complex shape.
The present invention overcomes these and other problems by providing a lower cost unitized cage for cylindrical roller bearings which maintains the alignment of cylindrical rollers.
The present invention resides in a unitized cage which incorporates a cage nest and a cage finger ring. The cage nest has a number of projections which allow the cage finger ring to be inserted onto and clamped into place by the cage nest. Additionally, the cage nest and cage finger ring can be manufactured from sheet steel or high strength polymer, and the two pieces do not have to be made from the same material for a given assembly: e.g., metal cage nest and polymer cage finger ring.
The present invention offers a number of advantages. The configuration of the cage nest is strong enough axially to control roller skewing and axially position the rollers. The cage nest-cage finger ring unitizing mechanism is strong enough to hold through harsh operating conditions, thus allowing for disassembly of the component and routine maintenance to occur. The cage nest and cage finger ring also have a simple geometry which allows for easy molding of the cage components from high strength polymer or stamping and forming from sheet metal for economical manufacturing. The subassembly can also be delivered xe2x80x9cpre-greasedxe2x80x9d to allow for simplification of the end user""s machine assembly. For this arrangement, the grease would be packed into the cage (around the rolling elements) and the subassembly would then be vacuum-sealed in a plastic bag to retain the grease during shipping.
The present invention also resides in the various embodiments of the above invention.